take the baffle out. i did today for shtz n giggles. its louder than ****, but on the bright side my bike would run like a a bat out of **** and have no problem reving up higher than normal.
we raced stand up scooters for years,and my friend has built two stroke pipes for more than 30 years.this pipe works very well. as for the w31, i have a 69 F85 w31 take a look it's on the top of the page.